拦截器

1.编写一个拦截器实现HandlerInterceptor接口

2.拦截器注册到容器中（实现WebMvcConfigurerAdapter的addInterceptors）

3.指定拦截规则（如果是拦截所有，静态资源也会被拦截）

InterceptorConfig代码

package com.xt.cn.springboot.interceptor.config;
 
 
import com.xt.cn.springboot.interceptor.interceptor.LogCostInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
 
@Configuration
public class InterceptorConfig extends WebMvcConfigurerAdapter{
 
    @Override
    public void addInterceptors(InterceptorRegistry registry){
        //registry.addInterceptor(new LogCostInterceptor()).addPathPatterns("/**");
        registry.addInterceptor(new LogCostInterceptor()).addPathPatterns("/test1");
        registry.addInterceptor(new LogCostInterceptor()).addPathPatterns("/test2");
        super.addInterceptors(registry);
    }
}

LogCostInterceptor代码

package com.xt.cn.springboot.interceptor.interceptor;
 
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.PrintWriter;
import java.util.Enumeration;
 
public class LogCostInterceptor implements HandlerInterceptor {
    long start = System.currentTimeMillis();
 
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        /*HttpSession session = request.getSession();
        session.setAttribute("user","zhangsan");
        session.setAttribute("pwd",123456);
 
        Enumeration<String> attributeNames = session.getAttributeNames();
        while (attributeNames.hasMoreElements()){
            String k = attributeNames.nextElement();
            System.out.println(k+"--"+session.getAttribute(k));
        }*/
 
        String userName = request.getParameter("username");
        System.out.println("请求执行之前：userName="+userName + "111");
 
        return true;
    }
 
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        String userName = request.getParameter("username");
        System.out.println("请求执行之后：userName="+userName + "222");
    }
 
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
 
    }
}

Test1Controller代码

package com.xt.cn.springboot.interceptor.controller;
 
import org.springframework.web.bind.annotation.*;
import javax.servlet.http.HttpServletRequest;
 
@RestController
public class Test1Controller {
 
    @GetMapping("/test1")
    public String test(HttpServletRequest request, String username) {
        System.out.println("controller中username=" + username);
        System.out.println("请求头中的Cookie信息：" + request.getHeader("Cookie"));
        return "123";
    }
 
    @GetMapping("/test2")
    public String test2(HttpServletRequest request) {
        return "123";
    }
}